El Camino del Rey
Back in 2003, I spent a month climbing the amazing limestone of El Chorro, Spain. There is enough rock there to keep you busy for a lifetime, and there is also an excellent range of route difficulties ranging from 5.9 to 5.13. You can choose from gorgeous tufa lined caves, stellar crimpy vertical climbs, and numerous bolted multipitch routes. A month certainly did not feel like enough time to really explore the area. One area, Makinodromo, can be accessed via the train tracks (which get a lot of traffic) or alternatively, you can walk El Camino del Rey. Wikipedia calls it El Caminito del Rey, and states that it was built as a walkway for worker to haul materials for building the nearby hydroelectric power plant. While I was there, I heard that it was built for the King to oversee the project. Who knows which is accurate, but the name seems to suggest the latter.
Here's a helmet-cam video showing